• Journal of Digital Convergence
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• v.14 no.6
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• pp.513-518
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• 2016

The Mechanisms of whole body vibration on the human body is not clearly presented despite of the research result and there is not enough research that shows the effects of vibration on the kinetic changes of the lower joint. Therefore, this study focuses on finding out which lower joint is related with kinetic vertical jump ability. Five male and five female who didn't have orthopedic history were selected as the subjects. The subjects carried out three squat jumps before and after 5minutes of 30Hz whole body vibration. We have utilized a 3D motion analysis system to analyze the kinetic changes of the lower joint in the vertical jump. The height of subjects squat jump was improved after whole body vibration treatment. Also, the lower joint moment and power increased. However, there were no statistically significant changes in GRF, hip joint moment and power after the whole body vibration proved to have positive effect on the ankle and knee joints but showed negative effect on the hip joint.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.397-402
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• 2003

Generally, container arrangement has been carried out based on the Classification guidelines. However, guidelines provide only container securing forces for the given container arrangement and Classification requirements of the forces. In order to design container arrangement additional information is needed such as container securing forces and arrangement that accounts for lashing bridges, vertical lashing, vertical center of gravity (VCG), and maximum stack weight. Trial and error method using the existing guidelines requires excessive amount of calculation time and cannot provide accurate results of the calculations. In order to fulfill this need, a new container securing system has been established based on the equilibrium conditions that include lashing bridges and vertical lashing. An optimization algorithm has been developed for the new system since current optimization methods such as genetic algorithms and evolution strategies are unsuitable for the container securing problems, which involve equality constraint. Design variables are container weights of tier and objective function is either total container weight or VCG of a stack. The newly developed system provides optimum arrangement of containers for both maximum stack weight and maximum VCG. It also greatly reduces time for designing container arrangement.

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.532-542
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• 2021

The purpose of this study was to investigate the body's strategy through kinematic variables of the lower extremities and ground reaction forces to maintain the club-head speed and ball accuracy despite the three stances during the golf swing. Ten male golfers who official handicap two were participate in the experiment. All subjects performed swing after maintaining the address posture according to stance conditions(square; SS, open: OS, closed: CS). Using a 3D motion analysis system and force plateform, the results were calculated with the 7-iron full swing each stance. In result, there was no difference in center of displacement, and left and right hip and knee joint angle displacement. Left ankle joint was largely plantar-flexed in OS, and right ankle joint was largely performed in CS from the address to the downswing. From address to take-back, right foot had a large left direction and the left foot had a right direction were greater in OS than in CS. Therefore, despite various stances, maintaining the same posture at impact is thought to have a positive effect on club head speed and ball direction.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.109-116
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• 2023

The purpose of this study was to investigate the influence of gender and load carriage difference on the lower extremity kinetics during stair descent. Ten healthy males and 10 healthy females were recruited (n=20). In the Maximum resultant velocity, it showed more velocity was decreased with difference by the change of gender (males>females) and load carriage (30%, 20%, 10%> 10%). And, resultant velocity showed interaction between gender and a load (load>gender). Main effect by gender during stair descent showed leg length was decreased in females than that of males at initial contact phase. Also, main effect by gender during stair descent showed more hip, knee flexed and plantar flexion of ankle joint in females than that of males. In the kinetics variables, main effect by gender during stair descent showed more higher reaction force of medial-lateral direction, and leg stiffness in males than that of females. We found that females successfully accommodated a load during stair descent by decreasing the range of motion of the hip joint angle and resultant velocity of movement. Males, on the other hand, require greater medial-lateral, vertical reaction force, and leg stiffness to accommodate a load, and control of momentum.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.424-433
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• 2019

The purpose of this study was to investigate the effects of gender difference in injury experience on biomechanical variables of lower extremity during two leg drop landing. 20 male(injury experience=8, non-injury experience=12) and 20 female(injury experience=11, non-Injury Experience=9) in their 20's were selected as subjects. Two-way mixed ANOVA was performed on the biomechanical variables obtained from the two leg drop landing in a 45cm height box and post-test was performed with bonferroni adjustment(p <.05). The results of this study suggest that the group of female who injury experience could induce the reduction of the peak vertical ground reaction force by increasing the valgus and internal rotation of the knee joint and flexion and internal rotation of the hip joint. In the INE(injury non-experienced) female group, the peak knee flexion angle was the smallest, as well as the flexion of the hip joint and the external rotation angle, and the peak vertical ground reaction force was the highest. On the other hand, the INE female group showed high vertical ground reaction force because they did not utilize the knee and hip joints relatively than the IE(injury experienced) female group, this means that it is relatively exposed to the risk of injury. Therefore, it was found that gender difference in injury experience is a factor affecting factors of knee and hip joint movement and peak vertical GRF(ground reaction force).

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.41-48
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• 2009

A flexible pipe was buried 10cm below the ground formed with standard sand to observe changes in the shape of the pipe according to the behavior of ground at each relative density. Changes in the shape of the pipe in each ground were observed to examine the behavior of the pipe under the state of reinforced ground after installing geogrid under the pipe. Ground reinforced using geogrid formed tensile force on the reinforcement material with increase in the vertical load and showed reduction in settlement under identical vertical load with existence of reinforcement. Distributions of ground deformation of 100% relative density and 70% relative density had clear difference. Reinforced ground with 70% density converged to the ground reaction of final settlement of non-reinforced ground with 100% density at final settlement of 100 mm. Because the shape of lower part strain of the buried pipe is similar to that of un-reinforced ground with relative density of 100%, reinforcement effect by geogrid in soft ground can be anticipated.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.487-495
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• 2003

Bearings at the obtuse corner are subjected to much larger vertical reactions than other bearings because of the geometric shape of skew bridges. The current relevant specifications require that additional bars should be disposed at the bottom of concrete deck slabs to deal with the large vertical reaction on bearings at the obtuse corner. In this study, new methods of reducing the magnitude of the vertical reaction on bearings at the obtuse corner by the stiffness adjustment of bearings were proposed. The basic concept of proposed methods was to redistribute support reactions by reducing the vertical stiffness of bearings at the obtuse corner showing a relatively large vertical reaction. For 45 simply supported skew bridges designed according to the current relevant specifications, the redistribution effect of vertical reactions by the stiffness adjustment of bearings was investigated. Parameters such as skew angle, girder spacing, and deck aspect ratio that affect the distribution of support reactions were considered. The results of the analyses show that the magnitude of the vertical reaction on bearings at the obtuse corner can be reduced to the levels of straight bridges by replacing the existing bearings at the obtuse corner with new ones having the value of 1/10 or 1/20 of the vertical stiffness of the existing bearings. The reduction effect of the vertical reaction on bearings at the obtuse corner increases as the girder spacing decreases and it is more pronounced when the deck aspect ratio is 2.0.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.57-64
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• 2007

The purpose of this study was to investigate comparative analysis of the vertical ground reaction force variables during landing from vertical jump blocking in volleyball through GRF analysis system. The subjects participated in this study were 6 male university volleyball player and 6 male acted as a control group. The results are as follows: 1. The skilled group was longer than the unskilled group in flight time during vertical jump blocking. 2. The skilled group was faster than the unskilled group in tFz2 during landing from vertical jump blocking. 3. The skilled group was higher than the unskilled group in Fz2 during landing from vertical jump blocking. 4. The skilled group was higher than the unskilled group in Fz2LR during landing from vertical jump blocking. 5. The skilled group was higher than the unskilled group in impulse during landing from vertical jump blocking. Consequently, during landing from vertical jump, the landing strategy of the skilled group was found as a form of a stiff landing. Therefore, this landing strategy will be required to strengthen of hip and knee extensors and ankle plantar flexors for injury prevention.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.615-618
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• 2016

This paper proposes a method to estimate vertical interaction force to the end of the surgical instrument by measuring reaction force at the part supporting the trocar. Relation between the force to the trocar and the interaction force is derived using the beam theory. The vertical interaction force is modeled as a function of the reaction force to the trocar and the distance between the drape plate and the trocar. Experimental results show that error is induced by the asymmetric shape of the trocar tip because contact position between the instrument and the trocar tip is changed depending on the direction of the interaction force. The theoretical relation, therefore, is compensated and reduced. Average $L_2$ relative error of the estimated force in the x-direction and the y-direction is 5.81 % and 5.99 %, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.17-27
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• 2019

In this paper, we study the applicability of Tuned Mass Damper(TMD) to improve seismic performance of piping system under earthquake loading. For this purpose, a mode analysis of the target pipeline is performed, and TMD installation locations are selected as important modes with relatively large mass participation ratio in each direction. In order to design the TMD at selected positions, each corresponding mode is replaced with a SDOF damped model, and accordingly the corresponding pipeline is converted into a 2-DOF system by considering the TMD as a SDOF damped model. Then, optimal design values of the TMD, which can minimize the dynamic amplification factor of the transformed 2-DOF system, are derived through GA optimization method. The proposed TMD design values are applied to the pipeline numerical model to analyze seismic performance with and without TMD installation. As a result of numerical analyses, it is confirmed that the directional acceleration responses, the maximum normal stresses and directional reaction forces of the pipeline system are reduced, quite a lot. The results of this study are expected to be used as basic information with respect to the improvement of the seismic performance of the piping system in the future.